Hands are one of the most difficult features on the human body to replicate. In art, science and life, hands have all the personality and complexity at the humans who wield them. We speak with them, we express our joy, sorrow, appreciation and anger with them. And we show our personalities through them.
Artist have for generations worked to capture the essence of their subject through hands, subtlety or overtly, with most portraits seeming incomplete without the hands present. The portrait of someone with their hands included adds that measure of expression to a person’s face and mood and personality.
On the other hand, when a person loses their hand through injury, illness or accident, they can sometimes feel at a loss of part of themselves. Not only is part of their interaction with the everyday world compromised (picking up a cup or riding a bike) but part of the way that the person expresses themselves is gone (running their hand through their hair in agitation, speaking excitedly with one’s hands in wild gestures of emphasis). If the lost hand was dominant, then they have to learn how to write with their non-dominant hand, because at the moment, the minute motor movements required to write cannot currently be done with most of the models of artificial hands currently on the market today.
One the reasons I believe this is so daunting is the complexity of the hand itself. It can seem fairly straight forward. Five digits on each hand, with the fingers each having three joints and the opposable thumb having two. The palm that is wide and strong enough to hold things such as pencils, books and the car door, which in turn articulates around the wrist.
However, looking at how the hand is actually constructed, we can see that the hand is a series of long and short bones starting at the wrist with the carpals (short bones), and ending in the long bones of the phalanges (fingers). The hand is created to be as flexible as possible so that we can curve it around apples and basketballs, and dexterous enough to hold pencils and rope. Currently there are a couple of hands that take this into account such as the hands made by touch bionics (www.touchbionics.com) though the palms are fixed and not flexible. At this current time, there are no “flexible” palms, but being able to gain the use of the hand in grabbing objects is more important for any amputee.
By focusing on how the hand is built from nature’s perspective, creating the finger joints to work not only as seamlessly as possible but with the user’s input by the use of muscle contraction such as in the e-Nable hands (www.enablingthefuture.org ) or by external powering with muscle signals, it helps to create a tool that the person can use to live as normal a life as possible.
While I am far from creating something so sophisticated at this point in time, I will be working on projects in a similar scope, starting with a baseline of a child’s hand printed out using a 3D printer. Once I have learned the basics for creating the artificial hand, I will be designing my own hands for prototyping and use.